Congress president Rahul Gandhi on Tuesday said Prime Minister Narendra Modi's silence on the gangrape of a 19-year-old board exam topper in Haryana was "unacceptable", adding that it was shameful on the part of the government to leave the country's women unprotected and allow rapists to walk free.

He also said the country's head hung in shame as another of its daughters was brutally gangraped.

"India hangs its head in shame as another one of its daughters is brutally gang raped.

"Prime Minister, your silence is unacceptable. Shame on a government that leaves India's women unprotected and afraid and allows rapists to walk free," Gandhi wrote on Twitter.

The Congress chief's remarks came as the Haryana Police failed to nab the main accused even after six days since the gangrape of the 19-year-old woman was reported.

The rape survivor, a board exam topper hailing from Rewari, was abducted from a bus stop in Kanina town of Mahendragarh district on Wednesday when she was on her way to a coaching class.

She was allegedly drugged and gangraped in a room adjoining a tubewell in an agricultural field, the police had said.